Field guns are typically provided with a mechanism to accommodate the high recoil forces generated when firing a round. One known recoil accommodation mechanism involves slidably mounting the barrel within a cradle so that the barrel can slide along its axes relative to the cradle. When a round is fired from the barrel, the barrel can counteract the momentum of the fired projectile by sliding backwards from a firing position (equilibrium position). This reduces the peak stresses induced in the field gun. The barrel can then return to its firing position so the field gun is ready for firing another round.
In addition to the recoil force a rifled barrel will also be subjected to a firing torque as a spin is imparted to the round by the rifling.
A gun employing such a known recoil accommodating mechanism is the M777 155 mm Lightweight Field Howitzer (M777). FIG. 1 shows an M777 cradle. In the M777, the breech end of the barrel is provided with at least one radially protruding lug. Each lug is disposed within a runner 202 that is attached to the sides of the cradle 200. The runner 202 extends away from the breech region 204 to a region 206 next to the point of maximum barrel recoil. The runner 202 serves to channel the lug (and hence the barrel) during recoil, and also serves to oppose rotation of the barrel that might be induced by the firing torque.
However, because this arrangement requires that the runners 202 (and hence the cradle 200) extend to the backmost portion of the recoil range, it restricts operator access to the breech. This increases reload time.
It is therefore an object of the invention to provide an interface between the barrel and the cradle that is not only resistant to firing torque but also leaves the breech readily accessible for loading by an operator.